The invention relates generally to wave solder systems, and more specifically to a fluxometer used for monitoring flux deposition.
Wave soldering is a common method of forming solder joints between electronic components and circuit traces on a printed circuit board (PCB). Typically, electronic components are placed on the PCB and their leads are inserted into holes in the circuit board such that the leads are in contact with metal pads or plating on vias to which they are eventually soldered.
A typical automatic wave soldering system includes conveyors driven to move the PCB at a constant speed from an entrance to an exit end of the system. The board is first carried to a fluxer where a spray of flux is applied to the bottom of the board. The PCB is then carried over heaters to evaporate excess flux deposits, activate the flux and minimize thermal shock. After the PCB is heated to a desired temperature, the board is passed over a solder pot to receive solder. The board is finally transported to a cool down zone where the solder is cooled and solidifies.
To ensure that all component leads are appropriately soldered, flux should be appropriately deposited such that it coats each component lead hole on the PCB even with the presence of leads of the electronic components. In general, components tend to solder better when the amount of flux deposited in the holes is sufficient. When the holes are partially coated, the boards may pass a testing stage but in time one or more of the component leads breaks away from the board due to poor soldering.
Several parameters of the fluxer are therefore set to ensure that flux is sprayed on to the PCB such that it properly contacts and/or fills each hole or via. Examples of fluxer parameters include atomization of the flux, a driving force of the fluxer spray, speed of a spray head of the fluxer, etc. The amount of flux deposition on the holes of the PCB directly depends on these fluxer parameters.
Typically, fluxer parameters are adjusted by testing a batch of PCBs that are first soldered using a set of fluxer parameters and subsequently making adjustments to the fluxer parameters based on the test results. This technique however is time consuming, expensive and may not render accurate settings for the fluxer. Fluxometers have been developed for testing application of flux to the desired regions of the board, but these are generally ineffective at accurately simulating and evaluating flux coverage.
Therefore, there is a need for a method and system to accurately set the parameters of the fluxer to ensure that the flux is appropriately deposited on printed circuit boards.